As adults, we're still chemical machines. There are a million knobs to tweak.
I was referring specifically to the DIY crowd, which this articles discusses. Things a Dr would say "no, I'm not going to help you with that". Or as the quote discusses, things a drunk person would say "I think this is a good idea".
It's a bizarre case that doctors will help normal people (journalists) experiment with some levels of sport doping, but it comes from knowing a little about the experimental professional sport dopers (where doctors try to stay anonymous.)
To give a different example, what about an anorexic that wants their genes to ensure their desired body image, i.e. 0 retention of normal fat? (Personally, I would be more concerned about bulk experiments in the beauty salons than the tattoo parlours.)
People buy whatever you tell them to buy, provided you give them an emotional reason to buy it. We just had someone try to sell to us in our home today, and when we told them the price was completely unreasonable, they tried to appeal to emotion (we need this sale to get a bonus, so we're willing to give you an awesome price...).
If you're a good enough salesman, you can sell air, as long as they think there's something different about your air.
Ok, scary thought already. But, casting aside all the safety concerns, how many attributes would someone in general want to change as an adult? You can't change your height, you can't change your hair color, you can't change your eyes. Is a myostatin-inhibitor going to be the "killer app" of DIY Crispr, so we can all look like a Belgian Blue cow?